When Charles Darwin published “The Origin of Species” in November 1859 geologists were still discussing the age of the earth. Deep time was an essential prerequisite to explain the recent biodiversity by gradual and slow changes in the remote past. However the calculations and criticism by physicists of the reconstructed geological age posed a great problem to evolutionists like Darwin and Wallace. Darwin didn’t address this problem in public, but he was convinced that the thickness of the stratigraphical column could only be explained by an ancient earth and the calculations of the physicists were based on wrong assumptions.